Large scale software-defined fiber optic patch-panels enable high bandwidth network interconnections within and between data centers to be automated. Current automated patch-panel technologies such as cross-bar switches scale unfavorably in complexity and size as N2, where N is the number of interconnects, significantly limiting their performance. Prior art descriptions of cross-bar switches include U.S. Pat. No. 4,955,686 to Buhrer et al., U.S. Pat. No. 5,050,955 to Sjolinder, U.S. Pat. No. 6,859,575 to Arol et al., and U.S. Patent Application No. 2011/0116739A1 to Safrani et al.
More recent automated patch-panel approaches that scale as N utilize braided fiber optic strands, wherein advances in the mathematics of topology and Knot and Braid Theory (U.S. Pat. Nos. 8,068,715, 8,463,091, 8,488,938 and 8,805,155 to Kewitsch) address the fiber entanglement challenge for dense collections of interconnect strands undergoing arbitrary and repeated reconfiguration. Since this Knots and Braids Switching (KBS) technology scales linearly in the number of interconnect strands, significant benefits over cross-bar switches in terms of density and hardware simplicity are realized.
These KBS-based fully automated patch-panel systems typically utilize a pick and place actuator with a gripper at one end of a robotic arm and sophisticated fiber routing algorithms implemented in control software. The robotic arm is of a sufficiently narrow width, typically less than 12 mm, to allow it to descend into the fiber optic interconnect volume without mechanical interference or contact with surrounding fiber strands. Strands potentially number in the thousands. The fiber switching system typically includes optical fibers in a lower section and a robot in the upper section. Since the internal fiber strands vary in length depending on the distance from their one dimensional backbone guide to the two dimensional array of internal ports, and this variation can be significant in large switching systems, a means of dispensing variable length interconnections has been implemented. This slack fiber management is typically achieved using a stacked arrangement of automatic spring loaded tack-up reels and low friction guiding elements to route these moving fibers through a common backbone and to their termination points across an array of connector ports. The KBS algorithm is necessary to fully automate the non-entangling reconfiguration of large scale, densely braided switches with several hundred to several thousand optical fiber cross-connect circuits, so that no human intervention to disentangle fiber is necessary.